What Will Happen if Vitamin A Is Deficient?

November 13, 2025 •

4 min read

According to the World Health Organization, vitamin A deficiency is the leading cause of preventable childhood blindness worldwide. So, what will happen if vitamin A is deficient? A lack of this essential nutrient can severely impact the body, leading to a cascade of health issues affecting vision, immune function, and overall well-being.

Quick Summary

A deficiency in vitamin A can cause a range of health issues, including eye problems like night blindness and xerophthalmia, weakened immune function, and skin dryness. Severe cases, particularly in children and pregnant women, can lead to irreversible blindness and increased mortality rates. Dietary intake and absorption issues are common causes.

Key Points

Night Blindness: An early symptom of vitamin A deficiency is poor vision in low-light conditions, which can lead to difficulty seeing at night.
Immunity Compromised: A deficiency weakens the body's immune system, increasing vulnerability to severe and potentially fatal infections, especially in children.
Skin and Growth Issues: Dry, scaly skin, rough bumpy patches (phrynoderma), and stunted growth in children are common systemic effects of VAD.
Irreversible Blindness: Prolonged and severe vitamin A deficiency can cause permanent damage to the cornea, leading to scarring and irreversible blindness.
Global Health Concern: Vitamin A deficiency remains a major public health problem in developing regions, being the leading cause of preventable blindness in children globally.
Treatment is Possible: Early-stage symptoms like night blindness are often reversible with vitamin A supplementation, highlighting the importance of timely intervention.
Dietary Prevention: Consuming a balanced diet rich in both preformed vitamin A (dairy, liver) and provitamin A carotenoids (carrots, leafy greens) is the primary way to prevent deficiency.

Understanding Vitamin A: A Critical Nutrient

Vitamin A, a fat-soluble vitamin, is crucial for numerous bodily functions, including vision, immune system health, reproduction, and cell growth. It is obtained from two primary sources: preformed vitamin A (retinoids) from animal products like liver, eggs, and dairy, and provitamin A carotenoids from plants, found in foods like carrots, sweet potatoes, and leafy greens. The liver stores a large portion of the body's vitamin A, mobilizing it when needed. However, when dietary intake is insufficient or absorption is compromised, a deficiency can develop, leading to a host of serious health consequences.

The Devastating Impact on Vision

One of the earliest and most well-known consequences of vitamin A deficiency (VAD) is its effect on eyesight. The vitamin is essential for producing rhodopsin, a pigment in the retina that is crucial for low-light vision.

Night Blindness (Nyctalopia): This is often the first symptom to appear. The eyes become unable to adjust properly to low-light conditions, making it difficult to see at dusk or in dark rooms.
Dry Eyes (Xerophthalmia): As the deficiency progresses, the conjunctiva (the membrane covering the whites of the eye) and the cornea become excessively dry, thickened, and wrinkled.
Bitot's Spots: These are foamy, triangular, or oval-shaped deposits that appear on the whites of the eyes, a classic clinical sign of VAD.
Corneal Damage: Severe and prolonged deficiency can lead to corneal ulcers and softening (keratomalacia), potentially resulting in irreversible vision loss and permanent blindness.

Compromised Immune System and Infection Risk

Vitamin A plays a vital role in maintaining the integrity of mucosal surfaces and the proper function of the immune system. A deficiency leaves the body highly vulnerable to infections.

Increased Vulnerability: The mucosal linings of the respiratory, gastrointestinal, and urinary tracts provide a crucial barrier against pathogens. VAD compromises this barrier, allowing bacteria and viruses to enter more easily.
Severe Infections: Infections like measles, diarrhea, and pneumonia are more frequent and severe in individuals with VAD, especially children. VAD is a major contributor to mortality from these childhood illnesses in developing countries.
Impaired Immune Response: VAD negatively affects the production and function of various immune cells, including T-cells and B-cells, dampening the body's overall ability to fight disease.

Effects on Skin, Growth, and Reproduction

Beyond vision and immunity, a lack of vitamin A has widespread systemic effects.

Dry and Scaly Skin: The skin relies on vitamin A for cell growth and differentiation. A deficiency can cause dryness, itchiness, and a bumpy, rough texture known as phrynoderma.
Stunted Growth: Vitamin A is essential for proper growth and development in children. Insufficient levels can lead to delayed growth and slowed bone development.
Reproductive Issues: VAD can cause infertility in both men and women and has been linked to poor pregnancy outcomes and higher maternal mortality rates.

Addressing and Preventing Vitamin A Deficiency

Preventing VAD involves a combination of dietary strategies and, in some cases, supplementation. For individuals with malabsorption disorders, regular monitoring and supplementation may be necessary.

Comparison: Natural Sources vs. Supplements


Feature	Natural Food Sources	Dietary Supplements
Types of Vitamin A	Preformed (retinoids) in animal products; provitamin (carotenoids) in plants.	Synthetic forms (retinyl acetate, retinyl palmitate) or beta-carotene.
Absorption	Generally well-absorbed, with absorption efficiency depending on food type.	Absorption can be more direct and concentrated.
Risk of Toxicity	Very low risk of toxicity from food alone, though liver is very high in vitamin A.	High doses can cause toxicity (hypervitaminosis A), especially from preformed vitamin A.
Bioavailability	Carotenoids may have lower conversion rates to active vitamin A than preformed vitamin A.	Provides a consistent and reliable dose of the required nutrient.
Nutrient Synergy	Comes with other nutrients and compounds that aid absorption and overall health.	Delivers a single or specific combination of nutrients.

Conclusion: The Importance of a Balanced Diet

In conclusion, the consequences of a vitamin A deficiency can range from mild, reversible symptoms like night blindness and dry skin to severe, life-threatening conditions such as permanent blindness and increased susceptibility to infectious diseases. While developed nations see fewer cases due to fortified foods and access to varied diets, VAD remains a significant public health issue in many parts of the world, disproportionately affecting vulnerable populations like children and pregnant women. The most effective prevention strategy is to ensure a balanced diet rich in both animal- and plant-based sources of vitamin A, such as liver, dairy, and a colorful array of fruits and vegetables. For those at risk due to malabsorption or living in endemic areas, supplementation under medical supervision can be a life-saving intervention. Prioritizing adequate vitamin A intake is not just about clear vision; it is about supporting a robust immune system and ensuring overall health and development. More information on vitamin A can be found on the Office of Dietary Supplements website.

The Key Takeaway

Early Signs: Night blindness (difficulty seeing in low light) is one of the earliest indicators of a vitamin A deficiency.
Eye Damage: Untreated deficiency can lead to severe eye conditions like xerophthalmia (dry eyes), Bitot's spots, corneal ulcers, and potentially irreversible blindness.
Weakened Immunity: A lack of vitamin A weakens the immune system and compromises mucosal barriers, increasing susceptibility to severe infections like measles and diarrhea.
Systemic Effects: VAD also manifests as dry, scaly skin, delayed growth in children, and negatively impacts reproductive health.
Global Impact: While rare in developed countries, vitamin A deficiency is a leading cause of preventable childhood blindness worldwide, particularly in developing nations.

Frequently Asked Questions

The most common and earliest symptom is night blindness (nyctalopia), which is the inability to see well in low-light or dark conditions.

Vitamin A deficiency impairs the function of immune cells and compromises mucosal barriers, making the body more susceptible to severe infections, particularly in the respiratory and gastrointestinal systems.

Yes. Severe and prolonged vitamin A deficiency can lead to xerophthalmia, corneal ulcers, and keratomalacia, which can result in permanent, irreversible blindness.

Primary causes include inadequate dietary intake, common in developing countries. It can also be caused by conditions that impair fat absorption, such as cystic fibrosis, celiac disease, or liver and pancreatic disorders.

Treatment involves taking high-dose vitamin A supplements, typically for several days, followed by lower doses until symptoms resolve. In severe cases, parenteral administration may be necessary.

No, it is rare in developed countries due to readily available fortified foods and varied diets. However, certain high-risk groups, such as those with malabsorption disorders or alcoholism, can be affected.

Foods rich in vitamin A include liver, eggs, dairy products, and fish, as well as orange and yellow vegetables like carrots, sweet potatoes, and squash. Dark green leafy vegetables also provide carotenoids.